The present invention relates generally to safety footwear, and more particularly, to safety boots and shoes that integrally incorporate a cushioned metatarsal guard protecting the metatarsal region (the instep region) of the wearer""s foot from injury caused by objects falling onto this region of the wearer""s foot.
The metatarsal region or in-step of the human foot extends forwardly from the ankle to the base of the toes and contains a number of elongated bones extending side by side. The in-step of the foot is particularly vulnerable to impact and crushing forces, especially those caused by falling or dropped objects. This region of the foot may also be injured by laceration or ,puncture by pointed objects or sharp edges encountered in industrial operations. Yearly, over 120,000 people are injured in such accidents. The American National Standards Institute (xe2x80x9cANSIxe2x80x9d) has developed a standard for footwear manufacturers to follow to ensure proper foot protection. The current standard is the ANSI Z41-1999 standard, which is approved by the Occupational Safety and Health Administration (OSHA). A certification under this standard for personal protective equipment including safety footwear is necessary to obtain consumer acceptance.
Footwear manufacturers have manufactured boots and shoes with a variety of metatarsal guards and cushions in an attempt to prevent the injuries described above. The most common method of protecting the metatarsal region is by placing a tough, rigid, synthetic plastic or metal shield over the exterior of the shoe to cover the metatarsal region of the foot. One example of such a shield is illustrated in U.S. Pat. No. 3,995,382, to Smith. This method of protecting the metatarsal region creates an unsightly and clumsy appearance of the shoe. Furthermore, the rigid shield limits the range of motion of the foot during walking or running. The external metatarsal shield also pinches the ankle when bending or squatting. More importantly, this type of metatarsal shield creates a snagging and tripping hazard which could cause extreme injury. The disadvantages described above create an uncomfortable safety shoe that most people do not like to wear.
Others have incorporated the rigid synthetic plastic or metal metatarsal shield into a fabric or leather cover usually matching the material the footwear is made from. This covered shield is then attached to the toe of the boot. In effect, the metatarsal shield becomes a second tongue placed over the exterior of the safety boot. This external shield does not solve the problems mentioned above which are associated with the uncovered, external metatarsal protectors. The shoes remain bulky and clumsy in appearance. Furthermore, the metatarsal protectors continue to be rigid, which prevents a full range of foot motion and results in fewer individuals wearing such protective equipment. Lastly, these types of metatarsal guards continue to present a tripping and snagging hazard.
In an attempt to create a more aesthetically pleasing and comfortable safety boot that minimizes the tripping and snagging hazard presented by external metatarsal shields, manufacturers have experimented with integrating metatarsal protectors into a boot. U.S. Pat. No. 4,102,062, to Adams, discloses a metatarsal protector made from rigid synthetic plastic material that is incorporated integrally into the boot. This method of protecting the metatarsal region continues to prevent the wearer of the boot from walking freely, and limits the range of motion of the foot because the rigid synthetic plastic material cannot bend or flex with the contours of the foot during walking or running. Because such safety boots cannot bend or flex properly, and are therefore uncomfortable, individuals are deterred from wearing such footwear. Furthermore, the integrated metatarsal protectors are not cushioned properly to prevent at least some pinching and other stresses from being inflicted on the metatarsal region of the foot.
The evolution of metatarsal guards has been advanced by others who have integrated hinged metal or plastic metatarsal guards into the safety footwear. Small pieces of metal or plastic are interlocked and riveted together to provide a flexible structure similar to linked armor of the middle ages. Because the separate pieces are overlapped and hinged together, the wearer""s foot is often pinched between the movable parts. Additionally, these types of guards have been found not to adequately distribute the impact forces of falling objects, which may thus result in point of contact injuries. Furthermore, upon impact forces or over time, the metal or plastic sections and the rivets can break loose. This can cause the safety footwear to become unwearable, or even worse, can seriously injure the wearer""s foot. As with other metatarsal protectors, this type of metatarsal guard creates an uncomfortable shoe that people do not want to wear.
To overcome the problems and disadvantages associated with the prior art, it is a primary objective of the present invention that it protect the metatarsal region of the foot from impacts or blows resulting from falling objects, as well as punctures and cuts from sharp objects encountered in the everyday workplace. This objective must be accomplished by meeting or exceeding the ANSI Z41-1999 standard. It is a further objective of the present invention that the guard be of a flexible nature to allow a full range of motion of the foot, which will provide the wearer with a boot or shoe that allows and conforms with natural walking or running movements. Furthermore, the guard of the present invention must be integrally positioned within the footwear to create an aesthetically pleasing appearance.
It is another objective of the guard of the present invention that it be light-weight and comfortable. It must be light enough so as to not fatigue the wearer. The guard of the present invention must also be flexible, with non-moving parts so as to prevent any pinching, cutting, or other irritation of the wearer""s foot.
It is yet a further objective of the present invention that it fully and completely protect the wearer""s foot from impact, puncture, cutting or blows to the metatarsal region and extending to the toes. The guard of the present invention, when used in conjunction with a protective toe cover such as a steel toe, must extend up to or beyond the protective toe cover to protect the entire metatarsal region of the foot. The guard of the present invention must also be able to withstand puncture or cutting caused by sharp objects or sharp points from objects. Additionally, the guard of the present invention must act to transfer and disperse impact forces from the region of impact to a broader region, thereby distributing the force. This will prevent a direct, single concentrated source of energy from the impact or blow, and prevent point-of-impact injuries to the wearer""s foot.
The guard of the present invention must also be of construction which is both durable and long-lasting, and it should require little or no maintenance to be provided by the user throughout its operating lifetime. In order to enhance the market appeal of a boot or shoe incorporating the guard of the present invention, it should also be of inexpensive construction to thereby afford at the broadest possible market. Finally, it is also an objective that all of the aforesaid advantages and objectives be achieved without incurring any substantial relative disadvantage.
The disadvantages and limitations of the background art discussed above are overcome by the present invention.
The present invention provides a safety boot or shoe with a cushioned metatarsal guard designed to protect the metatarsal region of a wearer""s foot from falling objects. In accordance with one aspect of the invention, a sole with a top surface and a bottom surface can be joined to an upper by stitching, adhesive, or a combination of both to form a cavity to accommodate the wearer""s foot. The upper has an exterior surface exposed to the elements and an interior surface facing towards the cavity. An inner lining may be attached to the interior surface of the upper by either stitching, adhesive, or a combination of both, and the inner lining may be made from leather, cotton, cambrelle, vinyl, polypropylene, tricot and velour or similar fabrics known by those skilled in the art.
When the inner lining is attached to the interior of the upper, a void is formed between the inner lining and the interior of the upper. The size and position of the void may vary depending on how and where the inner lining is attached to the upper. In accordance with an aspect of the present invention, the void can be positioned at the vamp, or otherwise known as the in-step region of the upper located above the metatarsal region of the wearer""s foot when placed into the cavity. An insert or metatarsal guard may then be placed into the void between the interior surface of the upper and the inner lining so that it sits above the metatarsal region of the wearer""s foot, thereby protecting it from falling objects.
The metatarsal guard in accordance with one aspect of the present invention can be a sandwich structure made up of different segments of materials layered over one another. The first layer may be a segment of cut-resistant material layer that is a flexible, thin, and lightweight fabric material, which can withstand protrusions, punctures, cuts and slices from sharp objects thereby protecting the wearer""s foot. DuPont manufactures an example of such a material under its trademark KEVLAR, although other types of fabrics are known by those skilled in the art.
The next layer may be a segment of force absorption material that can absorb and distribute an impact force from a falling object throughout the metatarsal guard. The force absorption material may have a plurality of air pockets to help absorb and distribute such forces, although the air pockets are not necessary to achieve the advantages of the present invention. Additionally, there may be more than one force absorption layer to absorb any impact forces. An example of a force absorption material is a two-part rubber based material with air pockets distributed throughout the material, similar to that manufactured by Esjot Goldenberg of Germany under its trademark META-TEC. Although this material is described herein, other force absorption materials known by those skilled in the art may also be used to substantially perform the same function.
The final layer of the sandwich forming the metatarsal guard may be an in-step cushion material that is lightweight, thin, and flexible. The in-step cushion should be of a pliable nature to accommodate the contours of the wearer""s foot. To meet these characteristics, the in-step cushion should be a urethane based foam, polyethylene, EVA or any other type of material known to provide both cushioning and shock absorption. The in-step cushion material covers the irregularities of the interior surface of the upper and the metatarsal guard to provide a uniform surface for the metatarsal region of the wearer""s foot resulting in additional comfort. Furthermore, the in-step cushion can absorb any impact forces dispersed from the force absorption material.
In accordance with another aspect of the present invention, the metatarsal guard can also include an impact cushion to absorb forces from falling objects and help define the shape of the metatarsal guard. The impact cushion should rest over the cut-resistant material so as to define the overall shape of the metatarsal guard, and can be made from a cross-linked polyethylene or other similar material known by those skilled in the art.
In accordance with a further aspect of the invention, the different layers of material forming the sandwich structure of the metatarsal guard can be affixed to one another by use of adhesives such as a rubber-based adhesive, double-sided tape, or a thin membrane with adhesive on both sides thereof which, until use, is covered with segments of release paper. The different segments of materials can be affixed to prevent any shifting or moving during use. The adhesive can be applied to a segment of cut-resistant material and affixed to the segment of force absorption material. The same or different adhesive may be applied between the force absorption material layer and the in-step cushion to affix the two segments together to form the metatarsal guard.
Should an impact cushion be used, the adhesive can affix the impact cushion to the cut-resistant material. Although the different layers of materials are described as being affixed to one another, it is apparent to one of ordinary skill in the art to omit using an adhesive to bind the materials together. Additionally, the order of materials comprising the metatarsal cushion can vary depending on manufacturing capabilities and preference.
The metatarsal guard as finally assembled may be secured within the safety shoe or boot by stitching that holds the metatarsal guard in place by joining the inner lining to the upper adjacent to and surrounding the metatarsal guard. The stitching then encloses the metatarsal guard within the void so it cannot shift or move during use. In accordance with other embodiments of the present invention, the metatarsal guard my be held to the inner lining by an adhesive such as a cloth tape, vinyl tape, or any other types of tapes or adhesives, or by a combination of stitching and adhesive materials. By securing the metatarsal guard to the inner lining, the metatarsal guard cannot shift or move during use.
The safety shoe or boot should have a rigid toe protector built into the shoe between the sole and the interior surface of the upper. The rigid toe protector has a cap or top portion in close adjacent to the interior surface of the upper and intermediate the inner lining and the interior surface of the upper. The rigid toe protector also has sidewalls that extend laterally downwards from the cap and are in substantial abutment with the sole. The rigid toe material may be made from such materials as tough plastic, steel, or other materials known to withstand impact forces. The metatarsal guard can overlay the rigid toe protector and in accordance with another embodiment of this invention, be adhesively attached to the rigid toe protector.
In accordance with a different aspect of the present invention, a method of making a cushioned, flexible metatarsal guard for use in safety footwear can include attaching an inner lining to an upper so that a void is formed between the two materials. The inner lining can be attached by stitching, adhesives, or a combination of both. The upper has an interior surface and an in-step or vamp region that covers the metatarsal region of a wearer""s foot. The void should be located near the in-step region of the upper. The upper should then be joined with a sole to form a cavity that will accommodate the wearer""s foot.
A metatarsal guard can then be assembled from different segments of materials in consecutive layer fashion. The first segment of material, the impact cushion, may be affixed to a segment of cut-resistant material by an adhesive, which may include a mixed rubber-based adhesive, double side tape, cloth tape or the like. The impact cushion can provide both impact absorption and shape to the metatarsal guard. A material such as cross-linked polyethylene foam material can be used, although it would be obvious by someone of ordinary skill in the art to use another type of material. The cut-resistant material protects the wearer""s foot from lacerations. Such a material should be thin, flexible and lightweight and should resemble the characteristics of a DuPont material marketed under the trademark KEVLAR.
Next, a segment of force absorption material can be affixed to the segment of cut-resistant material by an adhesive to form the metatarsal guard. The force absorption material should absorb and disperse the impact forces of falling objects. Rubber-based materials can be used including latex or rubber foam, vinyl, or other types of force absorbing materials known by those skilled in the art. An example of such a material is marketed under the trademark META-TEC by Esjot Goldenberg of Germany. An in-step cushion made from a urethane foam material, EVA, or other similar material may also be affixed to the force absorption layer by the same method to provide the wearer with additional comfort and shock absorption.
Finally, the metatarsal cushion can be inserted into the void between the upper and the inner lining to protect the wearer""s foot from falling or rolling objects. As discussed herein, the void should be positioned near the in-step region of the upper to protect the metatarsal region of the wearer""s foot. The metatarsal cushion should also be affixed to the inner lining to prevent the metatarsal guard from shifting or moving during use. This can be accomplished by affixing the metatarsal guard to the inner lining with an adhesive, such as adhesive tape or the like. The metatarsal guard can also be retained within the void by stitching the inner lining to the upper immediately surrounding the metatarsal guard. This will also prevent the metatarsal guard from shifting or moving during use. Although these two methods are described herein, it is obvious to those skilled in the art to use other methods to secure the metatarsal guard in place.
This invention overcomes the problems and disadvantages associated with the prior art by protecting the metatarsal region of the foot from impacts or blows, as well as from punctures and cuts, resulting from falling or rolling objects encountered in the everyday workplace. The present invention also meets or exceeds the ANSI Z41-1999 standard while providing a metatarsal guard that is of a flexible nature to allow a full range of motion of the foot, which will provide the wearer with a boot or shoe that allows and conforms with natural walking or running movements. Furthermore, the guard of the present invention is integrally positioned within the footwear to create an aesthetically pleasing appearance.
Additionally, the guard of the present invention is light-weight and comfortable to prevent fatigue of the wearer. The guard of the present invention is flexible, with non-moving parts so as to prevent any pinching, cutting, or other irritation of the wearer""s foot. Further, the metatarsal guard is located within the shoe or boot to eliminate the guard as a tripping or snagging hazard.
Furthermore, the present invention fully and completely protects the wearer""s foot from impact, cutting, puncture, or other blows to the metatarsal region and extending to the toes. The guard of the present invention, when used in conjunction with a protective toe cover such as a steel toe, extends up to or beyond the protective toe cover to protect the entire metatarsal region of the foot. The guard of the present invention also can withstand cutting caused by sharp objects or sharp points from objects. Additionally, the guard of the present invention acts to transfer and disperse impact forces from the region of impact to a broader region, thereby distributing the force and preventing point-of-impact injuries from a direct, single concentrated source of energy.
The guard of the present invention is also of a construction which is both durable and long-lasting, and it should require little or no maintenance by the user throughout its operating lifetime. The present invention is also of inexpensive construction to thereby afford at the broadest possible market.
Finally, all of the aforesaid advantages and objectives are achieved without incurring any substantial relative disadvantage.